Electric annunciator



June 13, 1933.

ATTORNEY P; H. CRAGO 1,913,699

ELECTRIC ANNUNCIATOR Filed Nov. 15, 1.929

19 1/ 3 PH B k 3 w INVENTOR PaaZ'H 6'? BY p Patented June13, 1933 vUNITED STATES PATENT OFFICE PAUL H. CRAGO, OF WILKINSBUBG, PENNSYLVANIA,ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE,PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA ELECTRIC mmmcu'ronApplication filed November 15-, 1929. Serial No. 407,323.

My inventionrelates to electric annunciators, and more particularly toan annunclator controlling system adapted to cause a signal to be givenupon the occurrence of a certain event, said signal beingdiscontinued-after a predetermined period of time even though thecondition causing the initial sounding of the signal still exists. Thiscondition may, for example, be the dropping of the armature of a trackrelay by the entry-of a train upon a particular section of track.

I shall describe herein one form of apparatus embodying my invention andshall point out the novelty thereof in claims.

The accompanying drawing is a diagrammatic view showing one form ofapparatus embodying my invention.

Referring to the drawing, the reference character 9 designates anordinary track relay, the armature 11 of which may be caused to drop bythe entry of a train upon the section of track 10, thus short-circuitingthe relay. The armature 11, uponbeing released, comes to rest uponcontact point 12, thus forming a current path through the coils ofrelays 13 and 14. Relays 13 and 14 are constructed in such manner thatthe current necessary to pick up the armature 15 of relay 13 is muchgreater than that necessary to pick up the armature 16 of relay 14. Whenin its lower position the armature 15 rests on the contact point 17,while the armature 16 makes contact at 18 only when it is attracted bythe relay 14 to its raised position. A rectifier 19 is shown connectedacross the relay 13 for a purpose to be later set forth. An electricbell is indicated at 20. 1

The operation of my annunciator controlling system is as follows:

The entry of a train upon the section of track 10 equipped with therelay 9 causes the armature 11 to drop and engage the contact 12. Acircuit is now established from one terminal B of a source of directcurrent not shown in the drawing, through said armature 11 and contact12 and thence through the coils of relays 13 and 14 to the oppositeterminal C of said source. There 18 now impressed upon said circuit bysaid source a .voltage suflicient to provide a current of a valueslightly greater than that required to pick up armature 15, but, owingto the inductance ofthe relay coils, the growth of current in thecircuit is retarded so that said current is held below the valuenecessary for picking up said armature. The armature of rela 14 and bell20 to the opposite terminal of said source.

The closing of the air gap in the relay 14 as armature 16 is broughtinto engagement with contact 18, serves to increase the inductance ofthe circuit, and thus further retards the building up of the currentthrough the relays 13 and 14. Thus an appreciable interval (which may beof the order of a sec- 0nd or so) will elapse before the armature 15 islifted, breaking the contact at 17 and opening the circuit through thebell 20. It will be seen therefore that the bell will ring only duringthis period, and will cease to ring when the current in the relaycircuit builds up to a point where it is suflicient to lift the armature15. The relay 13 is so constructed that the current necessary to liftits armature will be nearly as high as the Due to the characteristics ofthe relays and 14, when the current through them is interrupted, thearmature 15 may tend to be released before armature 16, thus causing thebell to ring again for a very short period. This action, however, isprevented by the rectifier 19, which is connected across the relay l3and causes the decrease of current in said relay to be retarded withrespect to the decrease of current in relay 14, causing the armature 16to be dropped before the dropping of armature 15.

It should be understood that, although I have here illustrated myinvention as applied to the control of an electric bell, any other formof signal could be substituted for this bell without affecting theoperation of the apparatus.

It should also be pointed out that my invention is in no way limited tothe control of an annunciator by a track circuit or by a track relay,but that any other form of control could be used in place of the contact1112 to control the relays 13 and 14.

The terms and expressions which I have employed are used as terms ofdescription and not of limitation, and I have no intention, in the useof such terms and expres- .sions, of excluding any equivalents of thefeatures shown and described or portions thereof, but recognize thatvarious modifications are possible within the scope of the inventionclaimed.

What I claim is:

1. In combination, a circuit, an inductive relay for closing saidcircuit in response to a flow of current through said relay, a relay forbreaking said circuit upon increase of said current to a given amount,means for causing direct current to flow through said relays against theinductance of said inductive relay, and a rectifier connected across thesecond mentioned relay.

2. In combination, an inductive relay, :1 second relay requiring for itsoperation a smaller current than that required for operation of saidinductive relay, means for at times applying to said relays in series adirect electromotive force of such magnitude that the initial currentflowing through said relays in opposition to the inductance of saidinductive relay ener izes onl said second relay while the su sequent yincreased current pro-duced by such electromotive force energizes bothsaid relays, and a circuit including a back contact of said inductiverelay and a front contact of said second relay.

3. In combination, an inductive relay, a second relay requiring for itsoperation a smaller current than that required for operation of saidinductive relay, means for at times applying to said relays in series adirect electromotive force of such magnitude that the initial currentflowing through said relays in opposition to the inductanceof saidinductive relay energizes only said second relay while the subsequentlyincreased current produced by such electro- November, 1929.

' PAUL H. GRAGO.

